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1.
Silicon - The nature of the opening silicate- based surface affects the chemical interaction, spectroscopic and antimicrobial efficiency. The aim of this approach was to evaluate the spectroscopic...  相似文献   
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Silicon - Magnesium calcium silicate nanostructures (MCSNS) loaded with (0.0, 0.6, 0.9, and 1.2 wt%) of Cephradine-drug consisting of mesoporous particles were functionally prepared by sol-gel...  相似文献   
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Based on gelatin (Gltn) and acrylic acid (AAc), biodegradable pH‐sensitive hydrogel was prepared using gamma radiation as super clean source for polymerization and crosslinking. Incorporation of PAAc in the prepared hydrogel was confirmed by Fourier transform infrared spectroscopy (FTIR). The effect of PAAc content on the morphological structure of the prepared hydrogel swollen at pH 1, 5, and 7 was examined using scanning electron microscopy (SEM). The results showed the dependence of the porous structure of the prepared hydrogels on AAc content and the pH of the swelling medium. Swelling properties of gelatin/acrylic acid copolymer hydrogels with different AAc contents were investigated at different pH values. Swelling data showed that the prepared hydrogels possessed pronounced pH sensitivity. In vitro release studies were performed to evaluate the hydrogel potential as drug carrier using ketoprofen as a model drug. Experimental data showed that the release profile depends on both hydrogel composition and pH of the releasing medium. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   
5.
Olive leaves (Kronakii cultivar) were obtained from the annual pruning of olive trees and pressed to obtain a crude juice. Aliquots from the concentrated crude olive leaf juice, representing 400, 800, 1600 and 2400 ppm as polyphenols, were added to sunflower oil. Samples of sunflower oil mixed with olive leaf juice were heated intermittently at 180 ± 5 °C for 5 h day?1 and the heating process was repeated for five consecutive days. A control experiment was performed where butylated hydroxyl toluene (BHT) at 200 ppm was added to sunflower oil prior to intermittent heating in order to compare the antioxidant efficiency between the natural polyphenolics of olive leaf juice and synthetic antioxidant BHT. Some physical and chemical constants for the unheated and heated sunflower oil were determined. The data indicate that the addition of olive leaf juice to sunflower oil heated at 180 °C induced remarkable antioxidant activity and at 800 ppm level was superior to that of BHT in increasing sunflower oil stability.  相似文献   
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In this paper we develop two pivotal quantities to construct exact predication intervals for future exponential lifetime based on a random number of lower generalized order statistics. The distribution functions of the two pivotal quantities, when the sample size is assumed to be integer-valued random variable, are derived. Three important special cases for the random sample size are presented. A simulation study is conducted for illustrative purposes.  相似文献   
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This paper presents an intelligent system for power quality assessment application. This system is used for power system model validation. A genetic algorithm (GA) based system for validating the power system model in capacitor switching studies has been developed. The problem formulation and the proposed solution are illustrated. The feasibility of the developed system for practical applications is demonstrated by evaluation studies.  相似文献   
8.
Hisham  Mohamed  Elmogy  Ahmed  Sarhan  Amany  Sallam  Alsayed 《Wireless Networks》2020,26(1):685-698
Wireless Networks - In Wireless Local Area Networks (WLAN), portable devices such as notebooks, tabs, and smart phones are powered by batteries with limited energy. With the great increase of using...  相似文献   
9.
Multicloud computing is a strategy that helps customers to reduce reliance on any single cloud provider (known as the vendor lock-in problem). The value of such strategy increases with proper selection of qualified service providers. In this paper, a constrained multicriteria multicloud provider selection mathematical model is proposed. Three metaheuristics algorithms (simulated annealing [SA], genetic algorithm [GA], and particle swarm optimization algorithm [PSO]) were implemented to solve the model, and their performance was studied and compared using a hypothetical case study. For the sake of comparison, Taguchi's robust design method was used to select the algorithms' parameters values, an initial feasible solution was generated using analytic hierarchy process (AHP)—as the most used method to solve the cloud provider selection problem in the literature, all three algorithms used that solution and, in order to avoid AHP limitations, another initial solution was generated randomly and used by the three algorithm in a second set of performance experiments. Results showed that SA, GA, PSO improved the AHP solution by 53.75%, 60.41%, and 60.02%, respectively, SA and PSO are robust because of reaching the same best solution in spite of the initial solution.  相似文献   
10.
A highly rapid process is described for the preparation of cellulose triacetate and its effect on particle size and surface area of the product. The process involves microwave-assisted rapid synthesis of cellulose triacetate with very low amount of acetic anhydride (10–15% of acetic anhydride is used in conventional methods) in the presence of iodine as a catalyst using a designed reaction vessel. The technique used is simple and rapid; it is also characterized by a high conversion ratio (yield 100%). A small amount of iodine (115 and 230 mg, 1.15 and 2.3% of cellulose weight) was found to be effective in the production of cellulose triacetate using 25, 30 to 40 mL acetic anhydride for 10 g cellulose under microwave irradiation for 2–4 min. The production of cellulose triacetate and the degree of substitution were confirmed by FTIR, Raman, 1H NMR, and thermogravimetric analysis. The optimal reaction condition was discovered to be 3 min microwave radiation and 30 mL acetic anhydride in the presence of 230 mg iodine for 10 g cellulose. The effects of the amount of acetic anhydride, and amount of catalyst and reaction time on the specific surface area, pore volume, mean pore diameter, and particle size distribution were investigated. The highest surface area obtained was 39.63 m2/g. The specific surface area and particle size distribution are highly dependent on the amount of acetic anhydride and I2 catalyst. About 10% of the synthesized cellulose acetate showed particle size less than 200 nm.  相似文献   
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